


You Can Always Count On Your Onee-Chan

by ruff_ethereal



Category: BanG Dream! (Anime), BanG Dream! Girl's Band Party! (Video Game)
Genre: Alternate Universe - Role Reversal, Bullying, Dominant Hikawa Hina, ESPECIALLY during sex, F/F, Futanari, Futanari Hikawa Sayo, Hina is the older twin, Humiliation, Incest, Sayo can't with how attractive and cute Hina can be, Sayo is the younger twin, Sibling Incest, Small Penis, Submissive Hikawa Sayo, Twincest
Language: English
Status: Completed
Published: 2019-08-16
Updated: 2019-08-16
Packaged: 2020-09-01 21:44:23
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 2,051
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20264983
Author URL: https://archiveofourown.org/users/ruff_ethereal/pseuds/ruff_ethereal
Summary: Sayo's left her libido unattended to for far too long, and now she finds herself totally distracted and unable to focus on anything else. She tries to handle it herself, but when she fails, her older sister Hina comes and helps her out, as usual.





	You Can Always Count On Your Onee-Chan

**Author's Note:**

  * Inspired by [perspective](https://archiveofourown.org/works/20230927) by [sayohjna](https://archiveofourown.org/users/sayohjna/pseuds/sayohjna). 

> This is an AU where the twin’s birth order is reversed, and Hina is the older, more responsible sibling, while Sayo is the younger sibling. I tried to keep their personalities more or less the same, except for some dramatic changes I hope make sense with the very different upbringing they had as a result.
> 
> Also, Sayo has a tiny penis and a ball sac, and Hina lightly bullies her as part of their dom/sub play.

It’s late at night as Sayo sits hunched over her desk, so much unfinished homework and notes before her, but all her attention focused on her cock as she tries to masturbate, relieve the pressure in her painfully full, aching balls. She only has her hand, her imagination, and her spit to work with, and unfortunately, her half-hard cock, the unpleasant roughness of her stroking, and her growing frustration all tell her they’re _definitely _not going to be enough.

Her eyes drift to her phone, laying at the edge of her desk. She thinks of calling Hina, get her help as usual, but quickly throws out the idea. _“This is _your_ problem, Sayo, deal with it yourself,” _she thought.

It was Sayo’s fault that she had been so overloaded with schoolwork, extracurricular activities, and band business all. It was Sayo’s fault that her few moments of free time rarely aligned with Hina’s, and if it did, she was too exhausted to want to do anything despite Hina’s usual enthusiasm. And it was Sayo’s fault that she hadn’t decided to drop some of those obligations, to take care of her increasingly distracting and discomforting libido.

Hina was busy with her own obligations—much more than Sayo had, or would ever be able to handle. Sayo didn’t want to—_couldn’t_—force her to use up Hina’s precious time to solve Sayo’s personal problem. It had happened _far _too many times already, and no matter how much Hina insisted that she didn’t mind, Sayo would--

“AGH!” Sayo cried as she let go of her cock, and pulled her panties back up. She winced at the sudden jolt of pain—did she give herself a friction burn from all her clumsy stroking? Frustrated and fuming, she launched off her seat, and stormed over to her drawer of cosmetics…

_Bang!_

… And accidentally banged her shin against one of her desk’s legs in the process, hitting it hard enough to send its contents shaking and rattling noisily. Sayo yelped, catching herself before she fell, hissing as she sat back down on her chair and examined her leg. She swore internally as she saw a light bruise already beginning to form.

Suddenly, a knocking on her door. “Sayo-chi…!” Hina called out. “Are you alright? I just heard a loud ‘bang’!”

Sayo swore again. _“Of course __Onee-chan __just happened to be around to hear it...” _she thought. “I’m fine…!” she replied, wincing.

“You don’t sound ‘okay’ at all, Sayo-chi...” Hina hummed. She tested the doorknob, found it locked. “Ah, can you please open the door, Sayo-chi? Or should I get the spare key?”

Sayo groaned, a resigned look on her face as she carefully put her injured leg on the floor—her shin ached, but fortunately not that much. “Don’t bother, I’ll get it myself!” she called out as she carefully made her way to her door.

Sayo found Hina outside holding a soda in one hand and a bag of chips in the other, a worried look on her face. Almost instantly, she was eyeing Sayo up and down, the bruise just one of the many things she inevitably noticed.

“What happened, Sayo-chi?” Hina asked.

“I got up too quickly from my chair and banged my leg against my desk.” Sayo said calmly.

“You did?” Hina asked. “I’m surprised, Sayo-chi, you’re usually a lot more graceful and coordinated than this!”

“Yeah, well accidents happen.” Sayo said as she began to close her door.

“Mhmm!” Hina hummed, nodding. “Guess it doesn’t help that you’ve been _really _distracted lately, haven’t you…?”

Sayo’s face betrayed nothing, but she froze for just a moment.

Hina smirked as she casually put her hand against the door, and pushed it back open. “Do you need my help, Sayo-chi? I know you don’t like asking for it, but you know you can always count on your Onee-chan to help!”

“It’s just a small bruise, it will heal quickly, and I’ll forget about it even faster.” Sayo said, trying to keep the tremble out of her voice.

Hina leaned in, bringing their faces so close together Sayo could feel Hina’s breath on her skin, couldn’t look away from Hina’s eyes as she stared directly into Sayo’s. “I didn’t mean the bruise, Sayo-chi~” she whispered.

Sayo chokes, staggers back and nearly tripped again, if it weren’t for the vice-grip she now has on the door.

“I’m coming in, Sayo-chi~” Hina hums as she casually waltzes through the gap Sayo had made.

Sayo tries to protest, but all she can do is stammer incoherently, sigh, then close the door and make triply sure it was locked again. Hina leaves her snack on Sayo’s headboard, before she sits down on Sayo’s bed, smiling as she says, “Come on, come on, Sayo-chi!”

With another sigh, Sayo comes to her like an obedient, trained puppy, sitting down beside Hina with her head down and her cheeks burning red. Hina reaches out and cups her cheek, coaxes Sayo to face her; Sayo does, feels her heart begin to race, all manner of emotions erupting inside her all at once.

“Why didn’t you ask me to help you, Sayo-chi…?” Hina asked softly.

“I… I didn’t want to bother you, Onee-chan.” Sayo said, eyes darting down and away from Hina’s face. “It’s my fault I let it get this bad, and you’re busy with your own problems...”

“I can always take a break from it all to take care of you, Sayo-chi.” Hina hummed. “In fact, I’m going to do just that,” she said with a nod.

Sayo balked. “Onee-chan, you don’t need to do this...” she mumbled.

“Sayo-chi?” Hina asked. “Look at me, please?”

Sayo reluctantly did, her eyes widened as she saw the serious, hard look on Hina’s face. “I _want _to do this, Sayo-chi. I know being Student Council President is important and all, but before I even ran, I was your Onee-chan.

“It’s always been my job to keep you safe, fed, and feeling good, and right now you’re not anywhere close to number three.” Hina’s face quickly broke out into a warm smile. “So let Onee-chan make you feel better, okay?”

Sayo gulped. “O-Okay…” she stammered.

Hina’s smile grew wider. “Boppin’,” she said, before she pulled away from Sayo, casually stole her blue pillow, and used it as a cushion as she knelt before Sayo.

Sayo spread her legs, quickly looked away to the side as Hina began to pull her skirt up and her panties down; she could rarely look at Hina directly when they got intimate, not without getting overstimulated. Hina understood this, but of course it had to come with a catch:

“Hello again, Sayo-chuu~! It’s been way too long since Onee-chan’s taken care of you, hasn’t it?”

Sayo cringed. _“__Please don’t use that godforsaken nickname...” _she thought as she blushed harder, her cock jerked and twitched in excitement.

“Ah, you’re so excited and ready to go, that’s so cute! But, Onee-chan needs to ask Sayo-chi what she’s supposed to do to you okay? Well, Sayo-chi...?”

“_You are a sadist.”_ Sayo thought as she mustered up the willpower to look at Hina, resist the urge to turn away as she sheepishly mumbled, “Please suck on it, Onee-chan.”

“Okay!” Hina said, beaming at Sayo before she turned her attention back to her cock. Hina gently picked it up with her calloused fingers, stroking it to get it fully hard, before she wrapped her lips around its head.

Sayo gasped as she felt the warmth and wetness of Hina’s mouth, mewled as she felt her lazily circle her tongue around her cockhead. “Is this boppin’ for you, Sayo-chi…?” Hina mumbled, her hands now slowly, lovingly caressing Sayo’s inner thighs.

Sayo forces herself to look down, just a glance at Hina’s smug, satisfied smile and her half-lidded eyes makes her cock jerk and throb, her heart race faster, her voice tremble and crack as she tried to say, “Yes, it’s boppin’, Onee-chan…”

_Pop._

Hina pulled out of Sayo’s cock, stroked it with her fingers as she asked, “What was that, Sayo-chi…? I couldn’t hear you very well!”

Sayo clenched fistfuls of her sheets, she shook as she whimpered, “Yes, it’s boppin’, Onee-chan!”

“But is it really…?” Hina says, dragging out the last word. “You don’t _sound _very convincing, Sayo-chi...~”

Had Sayo been a woman of much more willpower, and a whole lot less consideration and empathy for others, this might have been the moment when she let go of her sheets and grabbed fistfuls of Hina’s hair instead, forcibly shoved her cock back into her mouth, and put to words every last cruel, nasty, angry thought she’d ever had for Hina as she worked herself to an orgasm.

But she wasn’t, so she struggled, she squirmed, she took deep breaths to try to calm herself down, enough to say as clearly and enthusiastically as she could manage, “Yes, it’s boppin’, Onee-chan!”

Sayo closed her eyes and looked away from Hina immediately after—she knew wouldn’t be able to handle seeing just just how damn satisfied Hina was with herself, the grin on her face and the teasing look in her eyes.

Hina giggled. “Ah, you’re so cute, Sayo-chi~” she sang, before took Sayo’s cock into her mouth again.

After that, there were no more questions, no more words between them, just moans, hums, giggles, and whimpers. Hina never sped up or slowed down from her original pace, just made Sayo’s cock increasingly coated and drooling with her spit and pre-cum; the sucking, licking, and slurping noises all the louder and messier as her mouth became full of hot, gooey, bubbly mess; Sayo shiver and quake each time Hina slowly, _loudly _swallowed.

Sayo felt the pressure inside her grow, almost at her limit as she cried out, “Onee-chan!…”

_Pop._

Hina pulled out instantly, squeezed Sayo’s cock with her hand, and waited.

Sayo sucked in a deep breath, shuddered as she let it go. “Not yet…?” she whispered.

“Not yet,” Hina said. “Sorry, Sayo-chuu~!” she added, giggling.

Sayo blushed, and frowned. _“How long is Onee-chan going to make me wait…”_ she thought.

Quite a while, as it turned out.

Sayo didn’t know how for how long Hina kept it up—half-an-hour? A full hour? Maybe even more? Sayo couldn’t tell—it was already late at night, there wasn’t a moon out tonight, their parents probably already assumed they were asleep and unconscious themselves. Sayo couldn’t even figure out whether or not Hina was going to allow her to orgasm tonight—it wouldn’t be unlike her to punish her like that.

What she did know was that the aching and pain in her balls had gotten leaguues worse than they had started, almost—_almost_—overpowering the pleasure Hina was giving her. _“Onee-chan...” _Sayo moaned, her voice trembling and barely a whisper, little pathetic mewls following soon after.

_Pop._

“Yes, Sayo-chi…?” Hina asked, calm as could be.

“Cum…!” Sayo whimpered as she tried to look at Hina, _keep _her eyes on her. _“Please, _make me cum, Onee-chan… it hurts so bad, I_ need_ to cum!”

“Hmm...” Hina said, gently stroking Sayo’s cock with her fingers again, making Sayo start to tear her sheets from how tightly her nails were digging in. “And _why _should I do that…?”

“Because I love you, Onee-chan!” Sayo almost screams.

Hina smiles. “I love you too, Sayo-chi,” she hums, before she wraps her lips around Sayo’s cock again.

Soon after, Sayo all but _erupts__, _so much hot, gooey spunk gushing into Hina’s waiting mouth, down her throat and into her belly as she hungrily gulps it all down, all over her cheeks and face as she pulled out near the end of Sayo’s orgasm, eyes closed, mouth open, tongue out.

Sayo lets out the breath she was holding, completely frozen for a moment, before slowly falls backward onto her bed, completely limp, overwhelmed and exhausted.

Hina stood up, looming over Sayo, a grin on her face her one open eye shining, Sayo’s cum still dripping from her face. “You came _so much, _Sayo-chi~” she hummed. “Good girl!”

Sayo’s arms suddenly regain their strength, long enough to bring her hands flying onto her face.

“You just relax, Sayo-chi!” Hina says as she heads over to her drawers. “Onee-chan’s going to clean-up the both of us, okay?”

“Okay...” Sayo whispers.

**Author's Note:**

> "Chuu chuu" is Japanese onomatopoeia for a bird chirping, "birdie" is slang for the penis in my country, so "Sayo-chuu" is intended to roughly translate to "Sayo's Birdie."


End file.
